Functionalized polyherdral oligomeric silicon-oxygen clusters as cross-linking agents

ABSTRACT

The invention relates to a crosslinker for crosslinking matrix materials, to the matrix resulting therefrom, to the method employed therefor, and to the use of said crosslinker, the crosslinker comprising functionalized polyhedral oligomeric silicon-oxygen cluster units of the formula 
 
[(R a X b SiO 1.5 ) m (R c X d SiO) n (R e X f Si 2 O 2.5 ) o (R g X h Si 2 O 2 ) p 
         with a,b,c= 0 - 1 ; d= 1 - 2 ; e,f,g= 0 - 3 ; h= 1 - 4 ; m+n+o+p≧ 4 ; a+b= 1 ; c+d= 2 ; e+f= 3  and g+h= 4;  R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cyclo-alkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl group or polymer unit, which are in each case substituted or unsubstituted or further functionalized polyhedral oligomeric silicon-oxygen cluster units, which are attached by way of a polymer unit or a bridging unit, X=oxy, hydroxyl, alkoxy, carboxyl, silyl, alkyl-silyl, alkoxysilyl, siloxy, alkylsiloxy, alkoxy-siloxy, silylalkyl, alkoxysilylalkyl, alkylsilyl-alkyl, halogen, epoxy, ester, fluoroalkyl, isocyanate, blocked isocyanate, acrylate, methacrylate, nitrile, amino, phosphine group or substituents of the type R containing at least one such group of the type X, the substituents of the type R being identical or different and the substituents of the type X being identical or different.

The invention relates to a crosslinker for crosslinking organic and/orinorganic matrix materials, to the matrix resulting therefrom, to theprocess employed therefor, and to the use of said crosslinker, thecrosslinker comprising functionalized polyhedral oligomericsilicon-oxygen cluster units.

Crosslinkers are very important for producing materials based onplastics. For producing inorganic materials, as well, crosslinkingagents are essential for optimizing the properties.

In the case of organic matrix materials, curing takes place either bycooling after processing, such as with the thermoplastics, for example,or by subsequent crosslinking, such as with elastomers or thermosets,for example. This crosslinking can be carried out in a variety of ways.In many cases it is effected by exposing the matrix material tohigh-energy radiation. Another method is to produce free-radicalcompounds, which initiate crosslinking by way of double bonds in thepolymer, for example. Crosslinking may likewise take place by theaddition of crosslinkers having reactive groups, such as amino, hydroxy,isocyanate or epoxy groups, for example.

A crosslinker may act in two different ways. In the case of apolarmatrix materials, which have no functional groups for covalentattachment of the crosslinker to the matrix material, the crosslinkerreacts with itself to form an independent network in the matrix, thisnetwork being composed of the resultant structural units of thecrosslinker. Such a network is referred to as an “interpenetrating”network. A further type of crosslinking, in many cases the preferredmethod, is the attachment of the crosslinker to the matrix material byway of covalent bonds. The reactive functional groups in the crosslinkerand in the matrix material to be crosslinked must be matched to oneanother. For instance, both the matrix material and the crosslinker maycontain double bonds, hydroxyl groups, carboxyl groups, amino groups,isocyanate groups or epoxy groups. The reaction between matrix andcrosslinker is initiated by radiation, temperature, addition of moistureor addition of an initiator, so that covalent bonds are formed.Radiation used to initiate the process of crosslinking may compriseelectron beams, UV radiation or microwaves. Where the matrix materialscontain no functional groups, such as plastics based on polyolefins, forexample, then functional groups can be generated subsequently. After aprocess of this kind, such as flame treatment or corona discharge, forexample, hydroxyl and/or carboxyl groups are formed on the surface of aplastic and can be utilized for a reaction with the crosslinker.

For the formation of these covalent bonds there are a variety ofappropriate chemical reactions and reaction mechanisms, such as

-   -   esterification (hydroxyl group plus carboxylic acid or        carboxylic acid derivative group),    -   hydrosilylation (addition of an SiH group onto alkanes or        alkenes),    -   urethane formation (hydroxyl group plus isocyanate group),    -   urea formation (amino group plus isocyanate group),    -   amino alcohol formation (epoxy group plus amino group) or    -   formation of hydroxy ethers (epoxy group plus alcohol).

Elastomeric, thermoplastic, and thermoset plastics have a highelasticity. Generally, however, they have a low temperature stabilityand a low mechanical stability. The surfaces of organic matrixmaterials, such as plastics, are generally less resistant to abrasionand scratching than the surfaces of inorganic matrix materials.

Inorganic matrix materials may be cured by water, as in the case ofconcrete, or by atmospheric carbon dioxide, such as in the case ofmortar. In contrast to materials comprising organic matrices, materialscomprising inorganic matrices possess a high mechanical strength and ahigh temperature stability. However, being highly brittle, inorganicmaterials have a low elasticity. Furthermore, a controlled and, whereappropriate, rapid setting behavior is frequently required, as arehydrophobic properties in many cases.

It was therefore an object of the present invention to develop acrosslinker which raises the elasticity of inorganic matrices, such asconcrete, mortar or plaster, for example, before they set and does notadversely affect the adhesion or cohesion of organic matrices, e.g.,hotmelt adhesives, before they cure, but instead shortens their settingtime and raises the mechanical stability or strength and the temperaturestability.

Surprisingly it has been found that where crosslinkers containingfunctionalized polyhedral oligomeric silicon-oxygen cluster units areused in organic matrix materials the mechanical and thermal stability ofthe resultant material can be increased significantly. Furthermore, theuse of crosslinkers comprising functionalized polyhedral oligomericsilicon-oxygen cluster units raises the mechanical strength of theresultant organic material. The use of these crosslinkers of theinvention in powder coating materials based on isocyanates increasestheir adhesion, and the pot life of casting compositions based on epoxyresin is prolonged by virtue of their use. Although the various types ofcrosslinking and also the preparation of the polyhedral oligomericsilicon-oxygen clusters have already been known for a long time, it hasnot been recognized that these crosslinkers comprising functionalizedpolyhedral oligomeric silicon-oxygen cluster units in organic matrixmaterials are of essential importance for optimizing the properties ofmaterials. The solution to the problem was all the more surprising sinceit was found that these crosslinkers comprising functionalizedpolyhedral oligomeric silicon-oxygen cluster units likewise exhibit acrosslinking effect with inorganic matrix materials. The consequence ofthis is that the elasticity of these inorganic materials produced inthis way can be increased with the addition of chemical compoundscomprising functionalized polyhedral oligomeric silicon-oxygen clusterunits as a crosslinking agent.

By a polyhedral oligomeric silicon-oxygen cluster is meant, preferably,the two classes of compound represented by the silasesquioxanes and thespherosilicates.

Silasesquioxanes are oligomeric or polymeric substances whose fullycondensed representatives possess the general formula (SiO_(3/2)R)_(n),in which n≧4 and the radical R can be a hydrogen atom but is usually anorganic radical. The smallest structure of a silasesquioxane is thetetrahedron. Voronkov and Lavrent'yev (Top. Curr. Chem. 102 (1982),199-236) describe a synthesis of fully condensed and incompletelycondensed oligomeric silasesquioxanes by hydrolytic condensation oftrifunctional RSiY₃ precursors, where R stands for a hydrocarbon radicaland Y is a hydrolyzable group, such as chloride, alkoxide or siloxide.Lichtenhan et al. describe the base-catalyzed preparation of oligomericsilases-quioxanes (WO 01/10871). Silasesquioxanes of the formulaR₈Si₈O₁₂ (with identical or different hydrocarbon radicals R) can bereacted under base catalysis to functionalized, incompletely condensedsilasesquioxanes, such as R₇Si₇O₉(OH)₃, for example, or elseR₈Si₈O₁₁(OH)₂ and R₈Si₈O₁₀(OH)₄ (Chem. Commun. (1999), 2309-10; Polym.Mater. Sci. Eng. 82 (2000), 301-2; WO 01/10871) and thus can serve asparent compound for a host of different incompletely condensed andfunctionalized silasesquioxanes. The silases-quioxanes (trisilanols) ofthe formula R₇Si₇O₉(OH)₃ in particular can be converted intocorrespondingly modified oligomeric silasesquioxanes by reaction withfunctionalized monomeric silanes (corner capping).

Oligomeric spherosilicates have a construction similar to that of theoligomeric silasesquioxanes. They too possess a “cagelike” structure.Unlike the silasesquioxanes, owing to the method by which they areprepared, the silicon atoms at the corners of a spherosilicate areconnected to a further oxygen atom, which in turn is furthersubstituted. Oligomeric spherosilicates can be prepared by silylatingsuitable silicate precursors (D. Hoebbel, W. Wieker, Z. Anorg. Allg.Chem. 384 (1971), 43-52; P. A. Agaskar, Colloids Surf. 63 (1992), 131-8;P. G. Harrison, R. Kannengiesser, C. J. Hall, J. Main Group Met. Chem.20 (1997), 137-141; R. Weidner, Zeller, B. Deubzer, V. Frey, Ger. Offen.(1990), DE 38 37 397). For example, the spherosilicate with thestructure 2 can be synthesized from the silicate precursor of thestructure 1, which in turn is obtainable by the reaction of Si(OEt)₄with choline silicate or by the reaction of waste products from theharvesting of rice with tetramethylammonium hydroxide (R. M. Laine, I.Hasegawa, C. Brick, J. Kampf, Abstracts of Papers, 222^(nd) ACS NationalMeeting, Chicago, Ill., United States, Aug. 26-30, 2001, MTLS-018).

Both the silasesquioxanes and the spherosilicates are firmly stable attemperatures of up to several hundred degrees Celsius.

The present invention accordingly provides a crosslinker as claimed inclaim 1 for crosslinking matrix materials, the crosslinker comprisingfunctionalized polyhedral oligomeric silicon-oxygen cluster units of theformula[(R_(a)X_(b)SiO_(1.5))_(m)(R_(c)X_(d)SiO)_(n)(R_(e)X_(f)Si₂O_(2.5))_(o)(R_(g)X_(h)Si₂O₂)_(p)]

-   -   with a,b,c=0-1; d=1-2; e,f,g=0-3; h=1-4; m+n+o+p≧4; a+b=1,        c+d=2; e+f=3 and g+h=4;    -   R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cyclo-alkenyl,        alkynyl, cycloalkynyl, aryl, heteroaryl group or polymer unit,        which are in each case substituted or unsubstituted or further        functionalized polyhedral oligomeric silicon-oxygen cluster        units, which are attached by way of a polymer unit or a bridging        unit,    -   X=oxy, hydroxyl, alkoxy, carboxyl, silyl, alkyl-silyl,        alkoxysilyl, siloxy, alkylsiloxy, alkoxy-siloxy, silylalkyl,        alkoxysilylalkyl, alkylsilyl-alkyl, halogen, epoxy, ester,        fluoroalkyl, isocyanate, blocked isocyanate, acrylate,        methacrylate, nitrile, amino, phosphine group or substituents of        the type R containing at least one such group of the type X,    -   the substituents of the type R being identical or different and        the substituents of the type X being identical or different.

The present invention also provides for the use of the crosslinker ofthe invention in organic and/or inorganic matrix materials, and providesthe matrix resulting therefrom and the process employed therefor.

The crosslinker of the invention has the advantage that the resultingmaterials, based on one or more organic matrix materials, have increasedmechanical stability and mechanical strength, improved solventresistance, improved barrier behavior, increased adhesion, highertemperature stability and/or abrasion resistance and scratch resistanceon the surface. Moreover, the elasticity of inorganic materials can beraised by using chemical compounds comprising functionalized polyhedraloligomeric silicon-oxygen cluster units as crosslinking agent. Incontrast to many conventional crosslinkers, the characteristics of thecrosslinker of the invention can be controlled by way of thesubstituents of these polyhedral oligomeric silicon-oxygen cluster unitsand thus it is also possible to influence the properties of theresultant matrix. The crosslinker of the invention is able to react withitself and so form an independent network in the matrix, this networkbeing composed of the resultant structural units of the crosslinker ofthe invention, or else the crosslinker of the invention, with itsfunctional groups, is able to react with the functional groups of thematrix material and so bring about crosslinking of the matrix material.For the purposes of the present invention, the crosslinkers of theinvention may also be used as curing agents.

A feature of the crosslinker of the invention for crosslinking matrixmaterials is that the crosslinker comprises functionalized polyhedraloligomeric silicon-oxygen cluster units of the formula[(R_(a)X_(b)SiO_(1.5))_(m)(R_(c)X_(d)SiO)_(n)(R_(e)X_(f)Si₂O_(2.5))_(o)(R_(g)X_(h)Si₂O₂)_(p)]with a,b,c=0-1; d=1-2; e,f,g=0-3; h=1-4; m+n+o+p≧4; a+b=1, c+d=2; e+f=3and g+h=4;

-   -   R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cyclo-alkenyl,        alkynyl, cycloalkynyl, aryl, heteroaryl group or polymer unit,        which are in each case substituted or unsubstituted or further        functionalized polyhedral oligomeric silicon-oxygen cluster        units, which are attached by way of a polymer unit or a bridging        unit,    -   X=oxy, hydroxyl, alkoxy, carboxyl, silyl, alkyl-silyl,        alkoxysilyl, siloxy, alkylsiloxy, alkoxy-siloxy, silylalkyl,        alkoxysilylalkyl, alkylsilyl-alkyl, halogen, epoxy, ester,        fluoroalkyl, isocyanate, blocked isocyanate, acrylate,        methacrylate, nitrile, amino, phosphine group or substituents of        the type R containing at least one such group of the type X,    -   the substituents of the type R being identical or different and        the substituents of the type X being identical or different.

The use of crosslinkers of the invention comprising functionalizedpolyhedral oligomeric silicon-oxygen cluster units in organic matrixmaterials results in an increase not only in the mechanical stabilityand strength of the resultant materials but also in the thermalstability. Moreover, the elasticity of inorganic materials can be raisedthrough the use of chemical compounds comprising functionalizedpolyhedral oligomeric silicon-oxygen cluster units as a crosslinkingagent. In contrast to many conventional crosslinkers, thecharacteristics of the crosslinker of the invention can be controlled byway of the substituents of the functionalized polyhedral oligomericsilicon-oxygen cluster units and so the properties of the resultantmaterial can also be influenced. Accordingly, it is possible topredetermine the physical and chemical properties of the crosslinker ofthe invention. The polarity of the crosslinker of the invention can beadjusted by way of the substituents of the type R and X on thepolyhedral oligomeric silicon-oxygen cluster units. By way of thedifferent structure and polarity of these substituents it is possible tocontrol whether the polyhedral oligomeric silicon-oxygen cluster unitsare more inorganic or more organic in nature. Depending on structure,the crosslinkers of the invention may be of high thermal stability. As aresult of the cage structure of the polyhedral oligomeric silicon-oxygencluster units only a few functional groups are necessary for attachmentof the crosslinker molecules, since with one functionalized group it ispossible to attach an entire “cage”.

Preference is given to crosslinkers whose functionalized polyhedraloligomeric silicon-oxygen cluster unit is based on the structure 3

with X¹=substituent of type X or of type —O—SiX₃, X²=substituent of typeX, —O—SiX₃, R, —O—SiX₂R, —O—SiXR₂ or —O—SiR₃,

-   -   R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cycloalkenyl,        alkynyl, cycloalkynyl, aryl, heteroaryl group or polymer unit,        which are in each case substituted or unsubstituted or further        functionalized polyhedral oligomeric silicon-oxygen cluster        units, which are attached by way of a polymer unit or a bridging        unit,    -   X=oxy, hydroxyl, alkoxy, carboxyl, silyl, alkylsilyl,        alkoxysilyl, siloxy, alkylsiloxy, alkoxysiloxy, silylalkyl,        alkoxysilylalkyl, alkylsilylalkyl, halogen, epoxy, ester,        fluoroalkyl, isocyanate, blocked isocyanate, acrylate,        methacrylate, nitrile, amino, phosphine group or substituents of        the type R containing at least one such group of the type X,

The substituents of type X of the functionalized polyhedral oligomericsilicon-oxygen cluster units contain preferably isocyanate radicals,blocked isocyanate radicals, amino, acrylate, methacrylate, alkoxysilyl,alkoxysilylalkyl, hydroxyl and/or epoxy radicals. The polyhedraloligomeric silicon-oxygen cluster units of the crosslinker of theinvention are functionalized by way of the substituents of type X.

For certain fields of application, such as in the case of coatingmaterials, for example, it is possible to use crosslinkers havingblocked or capped isocyanate groups. In the case of the crosslinker ofthe invention, this functionality can be controlled through the choiceof the substituents of type X. For the field of use of coating materialsit is possible with preference to use crosslinkers containing polyhedraloligomeric silicon-oxygen cluster units with blocked or cappedisocyanate groups as substituents of type X. These crosslinkers of theinvention can be prepared, for example, by way of a ring formation, inwhich two isocyanate molecules form a uretdione or three isocyanatemolecules form an isocyanurate, or by a blocking procedure, withcaprolactam, phenols or malonic acid, for example.

In one particular embodiment of the crosslinker of the invention atleast two of the substituents are of the type X; in one particularlypreferred embodiment of the crosslinker at least two of the substituentsof the type X are identical.

On the basis of their molecular character, the crosslinkers of theinvention possess a uniform and defined molecular weight. In oneparticular embodiment of the crosslinker of the invention it has amolecular weight of preferably at least 400 g/mol, more preferably from700 to 3000 g/mol, and with particular preference from 800 to 1500g/mol.

The molecular size of the crosslinker of the invention can be increasedby joining two or more functionalized polyhedral oligomericsilicon-oxygen cluster units by means of condensation: for example, viaa spacer and/or the functional groups of the substituent of type X.Additionally, an enlargement of the crosslinker of the invention can beachieved by means of homopolymerization or copolymerization. Grafting isalso possible, i.e., the attachment of the crosslinker of the inventionto a larger molecule or polymer. For example, the polyhedral oligomericsilicon-oxygen cluster units can be joined to polymers byhydrosilylation. In this way it is possible to prepare molecules of morethan 5 nm in size (maximum extent of the crosslinker of the invention).It may also be advantageous if the crosslinker of the invention has amolecular size of from 0.1 to 500 nm, preferably from 0.5 to 50 nm, andwith very particular preference from 1 to 25 nm. In order to increasethe molecular size of the crosslinker of the invention it is possible touse dendrimer structures or hyperbranched structures.

In another embodiment the crosslinker of the invention may comprisefurther compounds having crosslinking properties, this combination ofdifferent crosslinkers including at least one crosslinker whichcomprises functionalized polyhedral oligomeric silicon-oxygen clusterunits.

The polyhedral oligomeric silicon-oxygen cluster units relate inparticular to the class of the spherosilicates of the formula[(R_(e)X_(f)Si₂O_(2.5))_(o)(R_(g)X_(h)Si₂O₂)_(p)] with e,f,g=0-3; h=1-4;o+p≧4; e+f=3 and g+h=4,but preferably to the class of the silasesquioxanes of the formula[(R_(a)X_(b)SiO_(1.5))_(m)(R_(c)X_(d)SiO)_(n)] with a,b,c=0-1; d=1-2;m+n≧4; a+b=1; c+d=2.

Particularly preferred crosslinkers are those based on thefunctionalized oligomeric silasesquioxane unit of structure 4, 5 or 6

with R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl,cycloalkynyl, aryl, heteroaryl group or polymer unit, which are in eachcase substituted or unsubstituted or further functionalized oligomericsilasesquioxane units which are attached by way of a polymer unit or abridging unit, the silasesquioxane unit being functionalized by way ofat least two hydroxyl groups.

The substituents of type R of the silasesquioxane units may all beidentical, producing what is termed a functionalized homolepticstructure[(RSiO_(1.5))_(m)(RXSiO)_(n)]  7with m+n=z and z≧4, z corresponding to the number of silicon atoms inthe framework structure of the polyhedral oligomeric silicon-oxygencluster unit, and

-   -   R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cycloalkenyl,        alkynyl, cyclo-alkynyl, aryl, heteroaryl group or polymer unit,        which are in each case substituted or unsubstituted or further        functionalized polyhedral oligomeric silicon-oxygen cluster        units, which are attached by way of a polymer unit or a bridging        unit,    -   X=oxy, hydroxyl, alkoxy, carboxyl, silyl, alkylsilyl,        alkoxysilyl, siloxy, alkyl-siloxy, alkoxysiloxy, silylalkyl,        alkoxysilylalkyl, alkylsilylalkyl, halogen, epoxy, ester,        fluoroalkyl, isocyanate, blocked isocyanate, acrylate,        methacrylate, nitrile, amino, phosphine group or substituents of        the type R containing at least one such group of the type X, the        substituents of the type R being identical or different and the        substituents of the type X being identical or different.

In another embodiment of the crosslinker the silasesquioxane unit has afunctionalized heteroleptic structure, in which at least two of thesubstituents of type R according to structure 7 are different.

The crosslinkers of the invention which comprise functionalizedoligomeric silasesquioxane units can be obtained by reactingsilasesquioxanes having free hydroxyl groups with monomericfunctionalized silanes of structure Y₃Si—X^(I), Y₂SiX^(I)X^(II), andYSiX^(I)X^(II)X^(III), the substituent Y being a leaving group selectedfrom alkoxy, carboxyl, halogen, silyloxy or amino group, thesubstituents X^(I), X^(II), and X^(III) being of the type X and beingidentical or different, where X=oxy, hydroxyl, alkoxy, carboxyl, silyl,alkylsilyl, alkoxysilyl, siloxy, alkylsiloxy, alkoxysiloxy, silylalkyl,alkoxysilylalkyl, alkylsilylalkyl, halogen, epoxy, ester, fluoroalkyl,isocyanate, blocked isocyanate, acrylate, methacrylate, nitrile, amino,phosphine group or substituents of type R containing at least one suchgroup of the type X, and R=hydrogen atom, alkyl, cycloalkyl, alkenyl,cycloalkenyl, alkynyl, cycloalkynyl, aryl, heteroaryl group or polymerunit, which are in each case substituted or unsubstituted or furtherfunctionalized oligomeric silasesquioxane units which are attached byway of a polymer unit or a bridging unit.

The general feature of a matrix of the invention is that it has beencrosslinked by means of at least one crosslinker of the invention. Thematrix has preferably from 0.05 to 100% by weight, more preferably from0.1 to 50% by weight, of the crosslinker of the invention, withparticular preference from 1 to 30% by weight, and with very particularpreference from 3 to 25% by weight of the crosslinker of the invention.Preference may also be given to a matrix crosslinked by means of acombination of different crosslinkers including at lest one crosslinkerof the invention. Where a combination of crosslinkers is used the matrixmaterial has an added amount of the crosslinker of the invention, basedon the matrix material to be crosslinked, of preferably from 0.1 to 25%by weight, more preferably from 1 to 20% by weight, and with particularpreference from 5 to 15% by weight. In the case of a combination ofcrosslinkers, the matrix material may include a prior art amount ofconventional crosslinkers. By way of example, crosslinkers of theinvention comprising oligomeric silasesquioxane units functionalizedwith isocyanate groups may be combined in any proportion withconventional isocyanate-based crosslinkers and used for the crosslinkingof hydroxyl-containing polyesters. Conventional isocyanate-basedcrosslinkers that can be used include isophorone diisocyanate (IPDI),2,4- and 2,6-tolylene diisocyanate (TDI), naphthylene 1,5-diisocyanate(NDI), diphenylmethane 4,4′-diisocyanate (MDI), triphenylmethane4,4′,4″-triisocyanate and/or hexamethylene diisocyanate (HDI). Inaccordance with the invention it is, however, also possible for thematrix to comprise exclusively the crosslinker of the invention, whichin that case combines the function of the matrix material and of thecrosslinker.

The matrix may comprise organic and/or inorganic matrix materials. Theinorganic matrix material of the matrix serves preferably to produceglasses, mineral building materials and/or inorganic sintercompositions. Alternatively, the matrix may comprise an elastomer,thermoplastic or thermoset. Particular preference is given to using anorganic matrix material comprising a polymer selected from polyethylene,polypropylene, polyester, copolyester, polycarbonate, polyamide,copolyamide, polyurethane, polyacrylate, poly-methacrylate,polymethacrylate copolymer, polysiloxane, polysilane,polytetrafluoroethylene, phenolic resin, polyoxymethylene, epoxy resin,polyvinyl chloride, vinyl chloride copolymer, polystyrene, styrenecopolymer, ABS polymer, alkyd resin, unsaturated polyester resin,nitrocellulose resin or rubber.

One particular embodiment of the matrix of the invention comprises anorganic matrix selected from hydrocarbon resins, polyamide resins, alkydresins, maleate resins, polyacrylates, urea resins, polyterpene resins,ketone-aldehyde resins, epoxy resins, phenolic resins, polyesters, andpolyurethane systems, cellulose derivatives, resins based on rosin,shellac and dammar, and all derivatives derived from the aforementionedresins. Such a matrix is suitable with preference for the preparation ofpaint systems and printing ink systems, with particular preference alsofor the preparation of powder coating materials.

In one particular embodiment of the matrix the crosslinker of theinvention forms preferably at least one, more preferably two, and withvery particular preference more than two covalent bonds to the matrixmaterial. For this purpose it is necessary for the reactive substituentsof type X of the crosslinker of the invention and the reactivefunctional groups in the matrix material to be crosslinked to be matchedto one another. For instance, both the matrix material and thecrosslinker of the invention may comprise double bonds, hydroxyl,carboxyl, amino, isocyanate or epoxy groups. By radiation, temperature,addition of moisture or addition of initiator the reaction between thematrix material and the crosslinker of the invention is initiated, andso covalent bonds are formed. The radiation used for initiating theprocess of crosslinking may comprise electron beams, UV radiation ormicrowaves.

In the case of apolar matrix materials, which have no reactivefunctional groups for covalent attachment of the crosslinker of theinvention to the matrix material, the crosslinker of the inventionreacts preferably with itself and so forms an independent network in thematrix, said network being composed of the resulting structural units ofthe crosslinker of the invention. In this case as well the process ofcrosslinking can be initialized by means of moisture, electron beams, UVradiation or microwaves.

The crosslinker of the invention can be used for crosslinking aninorganic matrix for producing glasses, ceramics, concrete, mortar,plaster and/or mineral building materials. This crosslinker of theinvention may likewise be used for preparing plastics, paints, inks,such as printing inks, for example, adhesives, sealants, castingcompounds, filling compounds, spreading compounds, foams, and coatings,which can be used both with organic materials and with inorganic ormetallic materials.

When the crosslinker of the invention with alkoxysilyl- oralkoxysilylalkyl-functionalized polyhedral oligomeric silicon-oxygencluster units is introduced into mineral substances, such as intoplasters, for example, the crosslinker of the invention preferablycontains a group which is capable of adhesion to mineral substances,which is able to react, for example, with the hydroxyl groups of themineral substance.

This particular embodiment of the crosslinker of the invention, withalkoxysilyl- or alkoxysilylalkyl-functionalized polyhedral oligomericsilicon-oxygen cluster units, can be used as a crosslinker of organiccoatings on glasses. This crosslinker is able both to crosslink thecoating and to react with the hydroxyl groups of the glass, therebyproducing good adhesion of the coating to the glass. The crosslinker ofthe invention can also be used for coatings of ceramics.

For producing coatings for glasses, but also for the coating ofplastics, crosslinkers of the invention can be used which compriseacrylate- or methacrylate-functionalized polyhedral oligomericsilicon-oxygen cluster units. The mixture used for the coating containspreferably from 0.05 to 100% by weight, more preferably from 5 to 95% byweight, and with particular preference from 10 to 60% by weight of thecrosslinker of the invention. The remaining amount may be an organicsolvent, in which the crosslinker of the invention may be dissolved ordispersed, a propellant gas or carrier gas and/or a suitable organicmatrix material, which together, for example, with the crosslinker mayform a multidimensional network, by polymerization, for example.Suitable propellant gases or carrier gases are preferably propane,butane, dimethyl ether, fluorinated hydrocarbons, nitrogen, dinitrogenmonoxide, air and/or gaseous carbon dioxide. Solvents used can bealiphatics, cycloaliphatics, halogenated hydrocarbons, cyclic ethers oracyclic ethers, for example. The coating is applied either by spreadingon, by spraying by means for example of “airless” apparatus orcompressed air guns, which have a pressure of from 2 to 20 bar and anozzle diameter of from 0.2 to 1.0 mm, or by spraying on using, forexample, spray cans, which have a pressure of from 1.2 to 10 bar and anozzle diameter of from 0.2 to 1.0 mm.

Crosslinkers of the invention comprising isocyanate-functionalizedpolyhedral oligomeric silicon-oxygen cluster units can be used, alone orin combination with conventional isocyanate-based crosslinkers, forcrosslinking polyols and/or hydroxyl-containing polyesters. Thisproduces coating materials, e.g., powder coating materials, but alsocasting, spreading, and filling compounds, and also adhesives, foams,and sealants.

The functionalization of the polyhedral oligomeric silicon-oxygencluster units of the crosslinker of the invention with an epoxy groupmakes it possible, in conjunction with hydroxyl-containing oramino-containing polyesters, to produce innovative epoxy systems forcoating materials, casting compounds, and adhesives.

From hydroxyl-containing polyesters it is possible, in combination withthe crosslinkers of the invention functionalized with hydroxyl groups,to produce reactive hotmelts and hotmelt adhesives or adhesives havingimproved mechanical stability and strength, improved solvent resistance,and higher temperature stability. As Dynacoll 7000

Degussa supplies hydroxyl-containing polyesters which are reacted at thepremises of the adhesives manufacturer with diisocyanates, such as MDIor IPDI, for example, depending on the desired degree of crosslinking.The customer applies these systems as hotmelt adhesives: throughabsorption of atmospheric moisture some of the free isocyanate groupsform an amine and react with the remaining isocyanate groups to form asubstituted urea, with subsequent polymerization and crosslinking of thehotmelt adhesive taking place in this way (Huber, M{overscore (u)}ller,Adhesives Age, November 1987, 32). By adding hydroxyl-functionalizedcrosslinkers of the invention and additionally adding diisocyanate orrecalculating the amount of diisocyanate (that is, taking account ofhydroxyl groups additionally introduced into the matrix byhydroxyl-containing crosslinker when determining the amount ofisocyanate overall) so as to maintain the desired 1:1 ratio of hydroxylgroups to isocyanate groups, it is possible to obtain bonds withmassively improved mechanical stability, strength, solvent resistance,and temperature stability.

By attaching an epoxy group to a polyhedral oligomeric silicon-oxygencluster unit of the crosslinker of the invention it is possible, inconjunction with hydroxyl-containing or amino-containing polyesters, onthe one hand to produce innovative epoxy systems for coating materials,casting compounds, and adhesives; on the other hand, by way of thefunctionalization of a polyhedral oligomeric silicon-oxygen cluster unitof the crosslinker of the invention with an amino group, it is possibleto cure the known systems comprising 1-chloro-2,3-epoxypropane andbisphenol A. A matrix of this kind is crosslinked in conventional mannerwith amines, such as isophoronediamine (IPDA), diethylene-triamine(DETA), triethylenetetramine (TETA) or tetra-ethylenepentamine (TEPA),for example. Here too it is possible to combine epoxy- oramino-functionalized crosslinkers of the invention with othercrosslinkers and/or curing agents in any proportion.

One particular application of the crosslinkers of the invention may befor coatings of chips in the computer industry. The systems of theinvention may have excellent insulator properties (low dielectricconstant), so that no notable capacitance is able to build up betweentwo conductor tracks. The term used by the skilled worker in this caseis a low k value, a low electrical permittivity. The systems of theinvention may accordingly have excellent credentials for use forcomputer chips. Preferably, in this case, the crosslinker of theinvention also represents the organic matrix itself, so that there is noabsolute need for an extraneous matrix.

The process of the invention for crosslinking matrix materials to form asolid matrix comprises using a crosslinker of the invention. Theindividual process steps can be conducted as for conventional processesof crosslinking. There is no need for any special process steps in orderto obtain the desired matrix.

The examples which follow are intended to illustrate the inventionwithout restricting the scope of its protection:

EXAMPLES 1 Preparation of the Silasesquioxanes Example 1.1 Synthesis of(isobutyl)₈Si₈O₁₂ from (isobutyl)Si(OMe)₃

To a solution of 446 g (2.5 mol) of isobutyltrimethoxy-silane(isobutyl)Si(OMe)₃ in 4300 ml of acetone there is added with stirring asolution of 6.4 g (0.11 mol) of KOH in 200 ml of H₂O. The reactionmixture is subsequently stirred at 30° C. for 3 days. The precipitateformed is filtered off and dried under reduced pressure at 70° C. Theproduct (isobutyl)₈Si₈O₁₂ is obtained in a yield of 262 g (96%).

Example 1.2 Synthesis of (isobutyl)₇Si₇O₉(OH)₃ from (isobutyl)₈SisO₁₂Example of the Synthesis of an Incompletely Condensed SilasesquioxaneHaving Three Free Hydroxyl Groups

At a temperature of 55° C. 55 g (63 mmol) of (isobutyl)₈Si₈O₁₂ areintroduced into 500 ml of an acetone/methanol mixture (volume ratio84:16) which contains 5.0 ml (278 mmol) of H₂O and 10.0 g (437 mmol) ofLiOH. The reaction mixture is subsequently stirred at 55° C. for 18 hand then introduced into 500 ml of 1 N hydrochloric acid. After stirringfor 5 minutes the solid obtained is filtered off and washed with 100 mlof CH₃OH. Drying in air gives 54.8 g (96%) of (isobutyl)₇Si₇O₉(OH)₃.

Example 1.3 Synthesis of (isobutyl)₇Si₇O₉(OSiMe₃)(OH)₂ Example of theSynthesis of an Incompletely Condensed Silasesquioxane Having Two FreeHydroxyl Groups

This compound is prepared by reacting the trisilanol(isobutyl)₇Si₇O₉(OH)₃ (from Example 1.2) with the chlorosilane ClSi(Me)₃using a base, such as triethylamine, with THF solvent at a temperatureof 20° C. Stirring is carried out overnight.

Example 1.4 Synthesis of (isobutyl)₇Si₇O₉(OSiMe₃)[OSiMe₂(CH₂)₃NCO]₂Starting from (isobutyl)₇Si₇O₉(OSiMe₃)(OH)₂ Example of a FunctionalizedSilasesquioxane Having Two Isocyanate End Groups

To a solution of 10 g (11.6 mmol) of (isobutyl)₇Si₇O₉(OSiMe₃)(OH)₂ in 50ml of THF containing 7 ml of triethylamine (Et₃N) there are added, at atemperature of 20° C., 4.29 g (25 mmol) of3-isocyanato-propyldimethylchlorosilane. The mixture is stirredovernight. Thereafter the solvent is removed under reduced pressure. Theproduct is isolated by extraction with 2×100 ml of hexane. The extractis stripped under reduced pressure to give a thick oil, which is thentaken up in 20 ml of toluene and precipitated by adding 100 ml ofacetonitrile. The yield of the product is 85%.

Example 1.5 Synthesis of (isobutyl)₇Si₇O₉[OSiMe₂(CH₂)₃NCO]₃ Startingfrom (isobutyl)₇Si₇O₉(OH)₃ Example of a Functionalized SilasesquioxaneHaving Three Isocyanate End Groups

To a solution of 10 g (12.6 mmol) of (isobutyl)₇Si₇O₉(OH)₃ in 50 ml ofTHF containing 10 ml of triethylamine (Et₃N) there are added, at atemperature of 20° C., 6.87 g (40 mmol) of3-isocyanato-propyldimethylchlorosilane. The mixture is stirredovernight. Thereafter the solvent is removed under reduced pressure. Theproduct is isolated by extraction with 2×100 ml of hexane. The extractis stripped under reduced pressure to give a thick oil, which is thentaken up in 20 ml of toluene and precipitated by adding 100 ml ofacetonitrile. The yield of the product is 89%.

Example 1.6 Synthesis of (isobutyl)₇Si₇O₉(OSiMe₃)[OSiMe₂(CH₂)₃NH₂]₂Starting from (isobutyl)₇Si₇O₉(OSiMe₃)(OSiMe₂H)₂ (from Hybrid Plastics)Example of a Functionalized Silasesquioxane Having Two Amino End Groups

To a solution of 4.0 g (4.1 mmol) of (isobutyl)₇Si₇O₉(OSiMe₃)(OSiMe₂H)₂in 25 ml of toluene there are added, at a temperature of 20° C., 0.51 g(9.0 mmol) of allylamine and 50 mg of aplatinum-divinyltetramethyl-disiloxane complex in xylene (from ABCRGelest GmbH & Co KG). The mixture is stirred overnight. Thereafter thesolvent is removed under reduced pressure. The product is precipitatedby adding 150 ml of acetonitrile, filtered off, and washed with 2×20 mlof acetonitrile. The yield of the product is 71%.

Example 1.7 Synthesis of (isobutyl)₇Si₇O₉[OSiMe₂(CH₂)₃NH₂]₃ Startingfrom (isobutyl)₇Si₇O₉ [OSiMe₂H]₃ (=SH1307 from Hybrid Plastics) Exampleof a Functionalized Silasesquioxane Having Three Amino End Groups

To a solution of 3.96 g (4.1 mmol) of (isobutyl)₇Si₇O₉[OSiMe₂H]₃ in 25ml of toluene there are added, at a temperature of 20° C., 0.80 g (14mmol) of allylamine and 50 mg of a platinum-divinyltetramethyldisiloxanecomplex in xylene (from ABCR Gelest GmbH & Co KG). The mixture isstirred overnight. Thereafter the solvent is removed under reducedpressure. The product is precipitated by adding 150 ml of acetonitrile,filtered off, and washed with 2×20 ml of acetonitrile. The yield of theproduct is 66%.

Example 1.8 Synthesis of(isobutyl)₇Si₇O₉(OSiMe₃)[OSiMe₂(CH₂)₃OCOC(Me)=CH₂]₂ Starting from(isobutyl)₇Si₇O₉(OSiMe₃)(OH)₂ Example of a FunctionalizedSilasesquioxane Having Two Methacrylate End Groups

To a solution of 10 g (11.6 mmol) of (isobutyl)₇Si₇O₉(OSiMe₃)(OH)₂ in 50ml of THF containing 7 ml of triethylamine there are added, at atemperature of 20° C., 5.52 g (25 mmol) of3-meth-acryloyloxypropyldimethylchlorosilane. The mixture is stirredovernight. Thereafter the solvent is removed under reduced pressure. Theproduct is isolated by extraction with 2×100 ml of hexane. The extractis stripped under reduced pressure to give a thick oil, which is thentaken up in 20 ml of toluene and precipitated by adding 100 ml ofacetonitrile. The yield of the product is 85%.

Example 1.9 Synthesis of (isobutyl)₇Si₇O₉[OSiMe₂(CH₂)₃OCOC(Me)=CH₂]₃Starting from (isobutyl)₇Si₇O₉(OH)₃ Example of a FunctionalizedSilasesquioxane Having Three Methacrylate End Groups

To a solution of 10 g (12.6 mmol) of (isobutyl)₇Si₇O₉(OH)₃ in 50 ml ofTHF containing 10 ml of triethylamine there are added, at a temperatureof 20° C., 8.83 g (40 mmol) of3-meth-acryloyloxypropyldimethylchlorosilane. The mixture is stirredovernight. Thereafter the solvent is removed under reduced pressure. Theproduct is isolated by extraction with 2×100 ml of hexane. The extractis stripped under reduced pressure to give a thick oil, which is thentaken up in 20 ml of toluene and precipitated by adding 100 ml ofacetonitrile. The yield of the product is 85%.

Example 2 Tests Example 2.1 Testing as a Hotmelt Adhesive Coating

In a three-necked round-bottomed flask 1 mol of polyester correspondingto the composition of Table 2.1.1, having a hydroxyl number of 30, ismelted at a temperature of 130° C. and degassed by applying reducedpressure for 30 minutes. Thereafter, at a temperature of 120° C., 2.2mol of diisocyanate or triisocyanate are added with stirring andhomogenized. Stirring is continued in the absence of moisture at 120° C.for the complete reaction of the components.

Setting Time

To measure the setting time, the hotmelt adhesive is applied thinly fromthe melt, which is at 120° C., to a 25×25 mm wooden block andimmediately thereafter this block is joined or adhesively bonded with asecond wooden block of the same base area. The setting time indicateshow long the pieces of wood can still be displaced relative to oneanother by means of strong finger pressure. The lower the period oftime, the more favorable the setting behavior of the hotmelt adhesive.

Bonding Tests

Inventive and noninventive polymer compositions according to Examples2.1 are prepared and then applied at a temperature of 120° C. to awooden test element. This wooden element is joined over an area of 4 cm²within 0.5 minute to a further wooden test element, with a simpleoverlap, and the wooden elements are pressed against one another with aweight of 2 kg for 5 minutes. The bonded specimen is then stored at 23°C. and 60% relative humidity for 14 days, after which a tensile test anda thermal stability test are conducted. The results are shown in Table2.1.1. TABLE 2.1.1 Composition of the hotmelt adhesives (1 mol) andtheir properties after reaction with 2.2 mol of diisocyanates ortriisocyanates Viscosity Tensile shear Composition at 130° C. HeatStability strength according of the (Brookfield, Non- Setting accordingto to DIN polyester Crosslinker in Pa s) inventive Inventive time(s) 68WPS (° C.) 53 283 (N/mm²) 50 mol % MDI 18 000 x 15 191 2.2 adipic acid +Crosslinker from 18 000 x 5 245 3.5 50 mol % Example 1.4 hexanediol 50mol % MDI + 50 18 000 x 9 207 2.9 mol % crosslinker from Example 1.4 25mol % MDI 12 000 x 10 185 2.3 adipic acid + Crosslinker from 12 500 x 4261 3.6 25 mol % Example 1.5 dodecanedioic 50 mol % MDI + 50 11 000 x 8212 3.0 acid + 50 mol % crosslinker mol % from Example 1.5 hexanediol

It is evident that using the crosslinkers of the invention rather thanconventional crosslinkers shortens the fitting time and allows markedimprovements in the tensile shear strength and thermal stability.

Example 2.2 Testing in Casting Resin Systems

As casting resins it is possible to use epoxy resin systems, which arenormally based on bisphenol A diglycidyl ether and amine curing agents,such as isophoronediamine (IPDA), for example. As a general rule, inorder to obtain optimum properties, it is important to attain as high aspossible a degree of curing. For that reason it is advantageous to usetwo kinds of reaction accelerants, namely those for controlling theprocessing time (pot life) and those for influencing the crosslinkingdensity. A further aim is to lower the maximum temperature duringcuring, since this goes hand in hand with reducing the shrinkage. DE 4211 454 describes a process for the preparation and the use ofisophoronediamine which is present 59% in trans form and 41% in cisform. Through the use of products from Examples 1.6 and 1.7 it ispossible to use commercial-grade IPDA having a trans content of 24% anda cis content of 76%.

Preparation of the Casting Resin System

In each case an epoxy resin based on bisphenol A diglycidyl ether(epoxide number 5.30 equivalents/kg, viscosity at 25° C. 10 500 mpas)and commercial-grade IPDA. For better through-curing, benzyl alcohol, inwhich the IPDA and the salicyl alcohol likewise used are initiallydissolved, is added. The results are shown in Table 2.2.1 TABLE 2.2.1Composition of the casting compounds and their properties König ServiceTemperature pendulum Non- life (min) rise ° C. hardness (s) Compositioninventive Inventive 10 g/23° C. (200 g batch) DIN 53157* 69% by weightepoxy resin x 74 190 208 + 15% by weight IPDA (76% cis, 24% trans) + 14%by weight benzyl alcohol + 2% by weight salicyl alcohol 68% by weightepoxy resin x 87 161 217 + 15% by weight IPDA (76% cis, 24% trans) + 14%by weight benzyl alcohol + 2% by weight salicyl alcohol + 1% by weightExample 1.6 68% by weight epoxy resin x 83 166 215 + 15% by weight IPDA(76% cis, 24% trans) + 14% by weight benzyl alcohol + 2% by weightsalicyl alcohol + 1% by weight Example 1.7*This coatings test was carried out on special metal panels - ChemetallNo. 129611 with Bonder rust protection 26/NL 60 - at a dry filmthickness of 45 +/−5 μm.

It is evident that the compositions of the invention as compared withconventional compositions have a longer service life, and a lowermaximum temperature with at least equally good or improved coatingperformance properties.

Example 2.3 Testing in an Inorganic Matrix (Mortar)

12.5 parts by weight of Portland cement, 12.5 parts by weight of limeand 75.0 parts by weight of weather sand (all components from thebuilder's merchant) are mixed with water to form a high-viscositymortar. 0.06 part by weight of each of the products from Examples 1.2,1.7 and 1.8 are incorporated homogeneously in various experiments withthe compositions of the invention. A rectangular mold of edge length150×20×5 mm is subsequently filled with this mortar at room temperatureand after one day this mixture is removed from the mold. The mortar isthen left to dry at room temperature for three days more. After dryingand demolding the test specimens are dropped horizontally from a heightof 1.50 m onto a concrete floor. The fracture behavior is assessed(Table 2.3.1). Following visual assessment, the scores 1 (very good) to5 (very poor) were awarded. TABLE 2.3.1 Composition of the inorganicmatrix and its properties Composition (parts Fracture by weight)Noninventive Inventive behavior 100 pure mortar x 5 100 pure mortar + x2 0.06 Example 1.2 100 pure mortar + x 3 0.06 Example 1.7 100 puremortar + x 3 0.06 Example 1.8

It is evident that the compositions have a higher elasticity andimproved fracture behavior as compared with conventional compositions.

The chemicals used in the examples were obtained from the followingsuppliers:

-   -   ABCR Gelest GmbH & Co KG (Postfach 210135; Hansastr. 29c;        D-76189 Karlsruhe)    -   Aldrich (P.O. Box 355; Milwaukee; Wis. 53201; USA)    -   Sigma-Aldrich Chemie GmbH (Postfach; D-80239 Deisenhofen)    -   Hybrid Plastics (18237 Mt. Baldy Circle; Fountain Valley, Calif.        92708-6117, USA)

1-28. (canceled)
 29. A matrix which has been crosslinked by means of atleast one crosslinker which comprises functionalized polyhedraloligomeric silicon-oxygen cluster units of the formula[(R_(a)X_(b)SiO_(1.5))_(m)(R_(c)X_(d)SiO)_(n)(R_(g)X_(h)Si₂O₂)_(p)]witha,b,c=0-1; d=1-2; e,f,g=0-3; h=1-4; m+n+o+p≧4; a+b=1, c+d=2; e+f=3 andg+h=4; R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cyclo-alkenyl,alkynyl, cycloalkynyl, aryl, heteroaryl group or polymer unit, which arein each case substituted or unsubstituted or further functionalizedpolyhedral oligomeric silicon-oxygen cluster units, which are attachedby way of a polymer unit or a bridging unit, X=oxy, hydroxyl, alkoxy,carboxyl, silyl, alkyl-silyl, alkoxysilyl, siloxy, alkylsiloxy,alkoxy-siloxy, silylalkyl, alkoxysilylalkyl, alkylsilyl alkyl, halogen,epoxy, ester, fluoroalkyl, isocyanate, blocked isocyanate, acrylate,methacrylate, nitrile, amino, phosphine group or substituents of thetype R comprising at least one such group of the type X, thesubstituents of the type R being identical or different and thesubstituents of the type X being identical or different and at least twoof the substituents being of type X.
 30. The matrix as claimed in claim29, wherein the crosslinker comprises functionalized polyhedraloligomeric silicon-oxygen cluster units, at least one of thesubstituents of type X comprising an isocyanate, blocked isocyanate,amino, acrylate, methacrylate, alkoxysilyl, alkoxysilylalkyl, hydroxylor epoxy group.
 31. The matrix as claimed in claim 29, wherein thecrosslinker comprises functionalized polyhedral oligomericsilicon-oxygen cluster units, at least two of the substituents of type Xare identical.
 32. The matrix as claimed in claim 29, which has beencrosslinked by means of a combination of different crosslinkers.
 33. Thematrix as claimed in claim 29, which comprises an organic and/orinorganic matrix material.
 34. The matrix as claimed in claim 29, whichcomprises as inorganic matrix material glasses, mineral buildingmaterials and/or inorganic sinter compositions.
 35. The matrix asclaimed in claim 29, which comprises as organic matrix material anelastomer or a thermoplastic or thermoset.
 36. The matrix as claimed inclaim 35, wherein the organic matrix material is a plastic selected fromthe group consisting of polyethylene, polypropylene, polyester,copolyester, polycarbonate, polyamide, copolyamide, polyurethane,polyacrylate, polymethacrylate, polymethacrylate copolymer,polysiloxane, polysilane, polytetrafluoro-ethylene, phenolic resin,polyoxymethylene, epoxy resin, polyvinyl chloride, vinyl chloridecopolymer, polystyrene, styrene copolymer, ABS polymer, alkyd resin,unsaturated polyester resin, nitrocellulose resin, rubber and mixturesthereof.
 37. The matrix as claimed in claim 29, wherein thesilasesquioxane unit of the crosslinker forms at least one covalent bondto the matrix material.
 38. The matrix as claimed in claim 29, whereinthe matrix material comprises from 0.1 to 50% by weight of thecrosslinker.
 39. A method of crosslinking matrix materials to form asold matrix, which comprises using a crosslinker which comprisesfunctionalized polyhedral oligomeric silicon-oxygen cluster units of theformula[(R_(a)X_(b)SiO_(1.5))_(m)(R_(c)X_(d)SiO)_(n)(R_(e)X_(f)Si₂O_(2.5))_(o)(R_(g)X_(h)Si₂O₂)_(p)]witha,b,c=0-1; d=1-2; e,f,g=0-3; h=1-4; m+n+o+p≧4a+b=1, c+d=2; e+f=3 andg+h=4; R=hydrogen atom, alkyl, cycloalkyl, alkenyl, cyclo-alkenyl,alkynyl, cycloalkynyl, aryl, heteroaryl group or polymer unit, which arein each case substituted or unsubstituted or further functionalizedpolyhedral oligomeric silicon-oxygen cluster units, which are attachedby way of a polymer unit or a bridging unit, X=oxy, hydroxyl, alkoxy,carboxyl, silyl, alkyl-silyl, alkoxysilyl, siloxy, alkylsiloxy,alkoxy-siloxy, silylalkyl, alkoxysilylalkyl, alkylsilyl alkyl, halogen,epoxy, ester, fluoroalkyl, isocyanate, blocked isocyanate, acrylate,methacrylate, nitrile, amino, phosphine group or substituents of thetype R comprising at least one such group of the type X, thesubstituents of the type R being identical or different and thesubstituents of the type X being identical or different and at least twoof the substituents being of type X.
 40. The method as claimed in claim39, wherein the crosslinker comprises functionalized polyhedraloligomeric silicon-oxygen cluster units, at least one of thesubstituents of type X comprising an isocyanate, blocked isocyanate,amino, acrylate, methacrylate, alkoxysilyl, alkoxysilylalkyl, hydroxylor epoxy group.
 41. The method as claimed in claim 39, wherein thecrosslinker comprises functionalized polyhedral oligomericsilicon-oxygen cluster units, at least two of the substituents of type Xare identical.